FIG. 1 is a perspective view illustrating a constitution of a related art crimp terminal described in Patent Document 1, for example.
A crimp terminal 101 is provided with an electric connection portion 110, which is provided in a front portion in a longitudinal direction of the terminal (a longitudinal direction of a conductor of an electric wire to be connected to the terminal) and connected to a terminal on a mating connector side, a conductor crimp portion 111, which is provided behind the electric connection portion 110 and crimped to an exposed conductor of an end of an electric wire (not illustrated), and a coated crimping portion 112 provided further behind the conductor crimp portion 111 and crimped to a portion with an insulating coating of the electric wire. The crimp terminal 101 is further provided with a first connection portion 113, which is provided between the electric connection portion 110 and the conductor crimp portion 111 and connects the electric connection portion 110 and the conductor crimp portion 111, and a second connection portion 114 provided between the conductor crimp portion 111 and the coated crimping portion 112 and connects the conductor crimp portion 111 and the coated crimping portion 112.
The conductor crimp portion 111 is formed to have a substantially U-shaped cross section by a bottom plate 111A, a pair of coated crimping pieces 111B, 111B provided to extend upwardly from both the right and left side edges of the bottom plate 111A and crimped so as to wrap a conductor of an electric wire disposed on an inner surface of the bottom plate 111A. The coated crimping portion 112 is formed to have a substantially U-shaped cross section by a bottom plate 112A and a pair of coated crimping pieces 112B, 112B provided to extend upwardly from both the right and left side edges of the bottom plate 112A and crimped so as to wrap an electric wire (portion with an insulating coating) disposed on an inner surface of the bottom plate 112A.
The first connection portion 113 and the second connection portion 114 provided respectively in front of and behind the conductor crimp portion 111 are formed to have a U-shaped cross section respectively by bottom plates 113A and 114A and low profile side plates 113B and 114B uprising from both the right and left side edges of the bottom plates 113A and 114A.
The bottom plates (the bottom plate 113A of the first connection portion 113, the bottom plate 111A of the conductor crimp portion 111, the bottom plate 114A of the second connection portion 114, and the bottom plate 112A of the coated crimping portion 112) ranging from the bottom plate (not illustrated) of the electric correction portion 110 on the front side to the coated crimping portion 112 on the tail end side are continuously formed into a band plate shape. The front and rear ends of a low profile side plate 113B of the first connection portion 113 are continued respectively to a lower half portion of a rear end of a side plate (reference numeral is omitted) of the electric connection portion 110 and a lower half portion of a front end of the conductor crimping piece 111B of the conductor crimp portion 111, and the front and rear ends of a low profile side plate 114B of the second connection portion 114 are continued respectively to a lower half portion of a rear end of the conductor crimping piece 111B of the conductor crimp portion 111 and a lower half portion of a front end of the coated crimping piece 112B of the coated crimping portion 112.
Among an inner surface 111R and an outer surface 111S of the conductor crimp portion 111, the inner surface 111R on the side in contact with the conductor of the electric wire is provided with a plurality of recessed groove-shaped serrations 120 extending in a direction perpendicular to a direction (terminal longitudinal direction) in which the conductor of the electric wire extends.
FIG. 2 is a detail view of the serrations 120 formed in an inner surface of the conductor crimp portion 111. FIG. 2(a) is a developed plan view of the conductor crimp portion 111, FIG. 2(b) is a IIb-IIb arrowed cross-sectional view of FIG. 2(a), and FIG. 2(c) is an enlarged view of a IIc portion of FIG. 2(b).
The cross-sectional shape of the recessed groove-shaped serrations 120 is a rectangular shape or an inverted trapezoidal shape, and an inner bottom surface 120A is formed substantially parallel to an outer surface 1115 of the conductor crimp portion 111. An inner corner portion 120C at which an inner side surface 120B and the inner bottom surface 120A intersect each other is formed as an angular portion at which a plane and a plane intersect each other. A hole edge 120D at which the inner side surface 120B and the inner surface 111R of the conductor crimp portion 111 intersect each other is formed as an edge.
As illustrated in FIG. 3, the conductor crimp portion 111 having the above serrations 120 is generally manufactured by pressing using a die 200 (actually, this is so-called a serration die which is assembled on an upper die of a press die) having protrusions 220 provided at positions corresponding to the recessed groove-shaped serrations 120.
In the die 200 in the above case, as illustrated in FIG. 4, since the protrusions 220 are linear, the die 200 is manufactured by grinding an upper surface of a block 210 with the use of a grindstone. FIG. 5 illustrates an external appearance of the die 200.
When the conductor crimp portion 111 of the crimp terminal 101 constituted as above is crimped to the conductor of the end of the electric wire, the crimp terminal 101 is placed on a placing surface (upper surface) of a lower die (anvil) (not illustrated), and, at the same time, the conductor of the electric wire is inserted between the conductor crimping pieces 111A of the conductor crimp portion 111 and placed on an upper surface of the bottomplate 111A. Then, an upper die (crimper) is relatively lowered relative to the lower die, whereby a front end side of the conductor crimping piece 111B is gradually pulled inward by a guide slope of the upper die.
The upper die (crimper) is then further relatively lowered relative to the lower die, whereby eventually the front end of the conductor crimping piece 111B is rounded so as to be folded back to the conductor side by a curved surface continued from the guide slope of the upper die to a central mountain-shaped portion, and the front ends of the conductor crimping pieces 111B are dug in the conductor while rubbing each other, whereby the conductor crimping pieces 111B are crimped so as to wrap the conductor.
According to the above operation, the conductor crimp portion 111 of the crimp terminal 101 can be connected to the conductor of the electric wire by crimping. Similarly, in the coated crimping portion 112, the coated crimping piece 112B are gradually folded inward by using lower and upper dies and crimped to a portion with an insulating coating of the electric wire. Consequently, the crimp terminal 101 can be electrically and mechanically connected to the electric wire.
When the crimping is performed, the conductor of the electric wire enters into the serrations 120 in the inner surface of the conductor crimp portion 111 by a pressure force while being plastically deformed, whereby connection between the crimp terminal 101 and the electric wire is reinforced.